Your fruit tree is grafted — Why? And so what?

We buy a fruit tree — a Pinkerton avocado, a Cara Cara navel orange, a Flavor King pluot — and we think the tag tells us what we’re getting, but it tells only half the story. Almost every fruit tree you buy has been grafted. In other words, almost every fruit tree is two trees in one. Why are they doubled up like this? And what difference does it make to us, as we care for it in our yard?

Why fruit trees are grafted

If you taste a Flavor King pluot from the tree in my yard and like it (and I think you will), and you decide that you’d like a Flavor King pluot tree of your own, you can’t plant the seed from that fruit and get a Flavor King pluot tree. You’d get a tree whose fruit was different, just like you’re different from your parents. Might be better, might be worse, but different for sure.

See pictures of how variable the fruit is from trees that all grew from Hass avocado seeds in this article.

That’s why fruit trees are grafted. Because it’s the only way to replicate them. (There are a few exceptions, like figs and pomegranates.)

What is grafting? In the simplest terms, it is connecting one tree to another, such that they fuse and grow together.

What happens is one tree is grown — usually from a seed — and it serves as the bottom half of the grafted tree, called the rootstock. If it’s a Flavor King pluot we want, then we take a piece of a branch from a Flavor King pluot tree and connect it to the rootstock tree. In the end, we’ll have two trees in one, where the roots and part way up the trunk are the rootstock tree, then there’s a graft union, and above that is the Flavor King pluot part that has branches and leaves and the Flavor King pluot fruit. The tree will make exactly the same fruit as the original Flavor King pluot. It is, in this sense, a clone.

So what?

It’s unfortunate that the labels that come on the fruit trees we buy do not tell us that the trees are grafted. They would also do well to warn us about rootstock suckers.

Have you identified the graft unions on your fruit trees? If not, I’d recommend doing so today. It could save the lives of your trees. Here are examples of graft unions on some of my trees.

A young Sharwil avocado; mature Blenheim apricot; Kishu mandarin.

You’re looking for a change in shape or color in the trunk, usually around six inches above the ground. That’s where the rootstock connects to the scion (the top part of the tree that gives the fruit you want). Sometimes the graft union is obvious, but particularly on old trees it can be hard to make out.

And here is the reason you want to locate this union: Any branch growing from below it must be removed, and hastily. A branch growing from below the graft union is called a rootstock sucker. If left to grow, it will probably eventually produce fruit, but its fruit will not be the Flavor King pluots or whatever kind of tree you bought. It’s fruit will be nasty, or at least strange.

Have you ever heard anyone say that their orange tree is producing some sour fruit? One of my neighbors said so, and she proffered that the orange tree might have cross pollinated with a nearby lemon. Nope. Doesn’t work that way. Rootstock suckers.

This brings us to the more urgent reason to remove rootstock suckers immediately. If left to grow, they often overtake the scion (e.g. Flavor King pluot). They shoot up very fast, grow taller than the top (scion) branches, shade them out and kill them. In time, your tree morphs from the tree you bought to a tree whose fruit is all mysterious.

When we moved into our house four years ago, there were many neglected fruit trees in the yard. The previous owners had been elderly and lost the interest or ability to care for them. One of the trees looked like a huge peach bush. That summer, it bore many small, bland peaches. Eventually, I climbed in and found that inside there was a thick trunk of an old peach tree that was now engulfed by numerous, more vigorous rootstock suckers. The old peach branches in the middle were barely still alive. I saved that old peach.

And notice how avocados are grafted using a different method in this video from an avocado nursery located in New Zealand. The same method (usually called “tip grafting”) is used in nurseries here in Southern California. The actual grafting can be seen starting at 1:45.

Thanks, Renee! I have to say that pluots in general have won me over. Dapple Dandy might be my favorite pluot, but they’re all a little different, they all taste great, they have a long harvest window, and at least in my yard, they grow so reliably every year.

Greg, can you tell us about how to treat an older tangerine tree that has so much fruit that it seems too heavy for the branches? Unfortunately, I do not know the type of tangerine but they usually are “ready” late December/early January.
Thank you so much!

An overperforming tangerine tree, eh? You’re probably safe doing nothing at all at this point. Since they’ll be ready to eat soon, it’s unlikely that they’ll get any bigger and heavier.

Citrus wood is amazingly flexible. I’ve personally never seen a citrus branch break under the weight of a heavy fruit load, even large oranges or grapefruit. My Valencia orange tree had an extremely heavy fruit load two years ago but nothing broke. My Gold Nugget mandarin had a very heavy load last year and nothing broke.

It certainly won’t hurt the tree if you thin the fruit from some laden branches, but it’s probably not necessary to prevent limb breakage. I say probably because I can’t see your tree, and it’s possible that something exceptional is going on with it.